Hi Nina, lead leg training is borrowed from outdoor cyclists. The drill builds mechanical efficiency and muscular endurance. Basically you focus on the usual round pedal stroke but also let one leg do all the work and the other come along for the ride. I coach intervals of 30-60 seconds and for riders to put enough tension on the bike so that they’re happy to hear it’s time to switch legs. Some also do a minute of one leg, 1 minute both legs, 1 minute the other leg. For indoor cycling it’s important to caution riders to keep both feet in the cages ad the weighted flywheel can give a nasty crack in the calf if riders try to put a foot on the crossbar. (Riders on trainers will often unclip one foot but they don’t have the weighted flywheel issue.)

I don’t know of any offhand but my instinct would be to look for remixes of good songs for jumps – the beat will probably still be amenable and the song will be longer. Let us know if you find some good ones!